Pharmacologically active compounds

ABSTRACT

The present invention relates to compounds of formula I shown below: 
                         
wherein Q is as defined herein. The compounds of formula I act as selective positive allosteric modulators of strychnine-sensitive alpha 1-glycine receptors. The present invention further relates to the use of these compounds as therapeutic agents for the treatment and/or prevention of diseases or conditions in which strychnine-sensitive alpha 1-glycine receptor activity is implicated (such as, for example, chronic pain. The present invention also relates to processes for the preparation of these compounds and to pharmaceutical compositions comprising them.

REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/587,068, filed May 4, 2017, which is a continuation of U.S.application Ser. No. 15/107,653, filed Jun. 23, 2016, which is the U.S.National Stage of International Patent Application No.PCT/GB2014/053838, filed Dec. 23, 2014, which claims the benefit of andpriority to Great Britain Patent Application No. 1322905.9, filed Dec.23, 2013. Each of the U.S. and International patent applications arehereby fully incorporated by reference herein.

INTRODUCTION

The present invention relates to pharmacologically active compounds.More specifically, the present invention relates to compounds that actas selective positive allosteric modulators of strychnine-sensitivealpha 1-glycine receptors. The present invention further relates to theuse of these compounds as therapeutic agents for the treatment and/orprevention of diseases or conditions in which strychnine-sensitive alpha1-glycine receptor activity is implicated (such as, for example, chronicpain or neuropathic pain). The present invention also relates toprocesses for the preparation of these compounds and to pharmaceuticalcompositions comprising them.

BACKGROUND OF THE INVENTION

In many clinical settings there is a need for safe and effective paincontrol strategies. However the majority of developments in the paincontrol field have failed to deliver high efficacy products free ofundesirable side effects and safety issues. The opiates are generallyregarded as the most effective treatment available for severe pain, butthe ultimate goal is to deliver a pain control agent with the efficacyof the opiates but without the sedation, dependence, gastric damage andgeneral tolerability problems that are associated with opiate use.

It has been postulated that phenol derivatives may have a number ofneuromodulatory effects. However the only phenol derivative inwidespread clinical use is the anaesthetic propofol(2,6-di-isopropylphenol).

Key features of anaesthesia are loss of consciousness, immobility in thepresence of painful stimuli and absence of recall. Anaesthetics, such aspropofol, are understood to mediate their anaesthetic effect byactivating γ-aminobutyric acid (GABA_(A)) receptors in the CentralNervous System (CNS).

Analgesia is defined as the relief of pain. Among other peripheraland/or central nervous mechanisms, analgesia can arise as a result ofenhanced inhibitory synaptic transmission within the dorsal horn of thespinal chord. It is understood that inhibitory postsynaptic transmissionin the spinal chord involves mainly glycine receptors. Accordingly theglycine receptor family represents a target site for therapeutic agentsaiming at inhibiting pain.

Both, GABA_(A) and glycine receptors belong to the ligand-gated ionchannel superfamily. They have a common structure in which five subunitsform an ion channel. α and ß subunits assemble into a pentamericreceptor with a proposed in vivo stochiometry of 3α: 2ß. Glycinereceptors, like GABA_(A) receptors, inhibit neuronal firing by openingchloride channels following agonist binding. Glycine receptors aremainly found in lower areas of the central nervous system and areinvolved in the control of motor rhythm generation, the coordination ofspinal nociceptive reflex responses and the processing of sensorysignals.

Chronic pain is very different from acute pain. Acute pain can beconsidered as a useful early warning system informing us about noxiousstimuli and thereby helping us to escape and prevent damage. Chronicpain, in contrast, is a disease in its own right. Experts regard it as adys-equilibrium syndrome, where inhibitory neuronal activity which undernormal circumstances suppresses the processing of pain is markedlyreduced. Treatment of chronic inflammatory or neuropathic pain is stilldifficult, and there is currently no single treatment that works for allconditions.

Increased neuronal excitability seen in chronic pain involves a loss ofinhibition mediated by GABA- and/or glycinergic neurons in thesuperficial dorsal horn of the spinal cord that control the relay ofnociceptive signals from the periphery to higher areas of the centralnervous system. In the adult dorsal horn, the contribution of glycine tofast inhibitory postsynaptic transmission dominates. Glycine receptorsare mainly found in lower areas of the central nervous system and areinvolved in the control of motor rhythm generation, the coordination ofspinal nociceptive reflex responses and the processing of sensorysignals. Their role in modulating ascending nociceptive pathways andpain makes them a potentially interesting target site for analgesic andspasmolytic agents. Microinjection of the glycine receptor agonisttaurine into the anterior cingulate cortex—associated with the affectivecomponent of pain—relieves neuropathic pain, an effect that could beantagonized by the selective glycine receptor antagonist strychnine.There are four α-subunits and one ß-subunit for the strychnine-sensitiveglycine receptor, the α1-subunit is widely expressed in the adult spinalcord and brain stem, but also in higher centres of the brain involved insensory processing. The glycine receptor α3-subunit has been identifiedas a target site underlying central inflammatory pain sensitization dueto PGE₂-induced receptor phosphorylation. α3-subunit knock-out mice donot develop inflammatory pain with otherwise normal response to acutepain. This phenomenon may be explained by the fact that α1 containingglycine receptor subunits which probably compensate for the lack in α3do not possess the protein kinase A (PKA) phosphorylation site involvedin the PGE₂ signal transduction. Furthermore, phosphorylation of the α3subunit is not necessarily involved in neuropathic pain. Based on thisunderstanding, a need has been identified by the inventors for thedevelopment of drugs that target the predominant adult glycine receptorisoform containing the α1 subunit. Given the physiological role ofglycine receptors and their relatively restricted expression (mainly inthe spinal cord and lower brain areas), a selective glycine modulatorshould be of great interest therapeutically to increase inhibition atthe level of the spinal cord dorsal horn.

There exists a need to develop new and improved analgesics. Despite thatfact that glycine receptors represent a good target for identifying suchanalgesics, there are no existing analgesics that effectively targetthese receptors. The inventors therefore decided to address this issueand exploited their knowledge of the pathophysiological mechanismsunderlying anaesthesia and analgesia with a view to identifying new andimproved drugs for controlling pain.

Aspects of the invention were devised with the foregoing in mind.

SUMMARY OF THE INVENTION

In one aspect, the present invention provides a compound, or apharmaceutically acceptable salt or solvate thereof, as defined herein.

In another aspect, the present invention provides a pharmaceuticalcomposition which comprises a compound as defined herein, or apharmaceutically acceptable salt or solvate thereof, and one or morepharmaceutically acceptable excipients.

In another aspect, the present invention provides a compound as definedherein, or a pharmaceutically acceptable salt or solvate thereof, or apharmaceutical composition as defined herein, for use in therapy.

In another aspect, the present invention provides a compound as definedherein, or a pharmaceutically acceptable salt or solvate thereof, or apharmaceutical composition as defined herein, for use in the treatmentof a disease or condition in which the selective, positive allostericmodulation of strychnine-sensitive alpha 1-glycine receptors isbeneficial.

In a particular aspect, the present invention provides a compound asdefined herein, or a pharmaceutically acceptable salt or solvatethereof, or a pharmaceutical composition as defined herein, for use inthe treatment of pain. In a particular embodiment, the pain is presentin a human subject.

In a particular aspect, the present invention provides a compound asdefined herein, or a pharmaceutically acceptable salt or solvatethereof, or a pharmaceutical composition as defined herein, for use inthe treatment of chronic pain. In a particular embodiment, the chronicpain is present in a human subject.

In a particular aspect, the present invention provides a compound asdefined herein, or a pharmaceutically acceptable salt or solvatethereof, or a pharmaceutical composition as defined herein, for use inthe treatment of neuropathic pain. In a particular embodiment, thechronic pain is present in a human subject.

In another aspect, the present invention provides a compound as definedherein, or a pharmaceutically acceptable salt or solvate thereof, or apharmaceutical composition as defined herein, for use in the selective,positive allosteric modulation of strychnine-sensitive alpha 1-glycinereceptors.

In another aspect, the present invention provides the use of a compoundas defined herein, or a pharmaceutically acceptable salt or solvatethereof, in the manufacture of a medicament for use in the treatment ofa disease or condition in which the selective, positive allostericmodulation of strychnine-sensitive alpha 1-glycine receptors isbeneficial.

In a particular aspect, the present invention provides the use of acompound as defined herein, or a pharmaceutically acceptable salt orsolvate thereof, in the manufacture of a medicament for use in thetreatment of pain. Suitably, the medicament is for use in the treatmentof pain in a human subject.

In a particular aspect, the present invention provides the use of acompound as defined herein, or a pharmaceutically acceptable salt orsolvate thereof, in the manufacture of a medicament for use in thetreatment of chronic pain. Suitably, the medicament is for use in thetreatment of chronic pain in a human subject.

In a particular aspect, the present invention provides the use of acompound as defined herein, or a pharmaceutically acceptable salt orsolvate thereof, in the manufacture of a medicament for use in thetreatment of neuropathic pain. In a particular embodiment, theneuropathic pain is present in a human subject.

In another aspect, the present invention provides the use of a compoundas defined herein, or a pharmaceutically acceptable salt or solvatethereof, in the manufacture of a medicament for use in the selective,positive allosteric modulation of strychnine-sensitive alpha 1-glycinereceptors.

In another aspect, the present invention provides a method ofselectively producing a positive allosteric modulation effect instrychnine-sensitive alpha 1-glycine receptors in vitro or in vivo, saidmethod comprising contacting a cell with an effective amount of acompound as defined herein, or a pharmaceutically acceptable salt orsolvate thereof.

In another aspect, the present invention provides a method of treating adisease or condition in which the selective, positive allostericmodulation of strychnine-sensitive alpha 1-glycine receptors isbeneficial in a patient in need of such treatment, said methodcomprising administering to said patient a therapeutically effectiveamount of a compound as defined herein, or a pharmaceutically acceptablesalt or solvate thereof, or a pharmaceutical composition as definedherein.

In another aspect, the present invention provides a method of treatingpain in a patient in need of such treatment, said method comprisingadministering to said patient a therapeutically effective amount of acompound as defined herein, or a pharmaceutically acceptable salt orsolvate thereof, or a pharmaceutical composition as defined herein.

In another aspect, the present invention provides a method of treatingchronic pain in a patient in need of such treatment, said methodcomprising administering to said patient a therapeutically effectiveamount of a compound as defined herein, or a pharmaceutically acceptablesalt or solvate thereof, or a pharmaceutical composition as definedherein.

In another aspect, the present invention provides a method of treatingneuropathic pain in a patient in need of such treatment, said methodcomprising administering to said patient a therapeutically effectiveamount of a compound as defined herein, or a pharmaceutically acceptablesalt or solvate thereof, or a pharmaceutical composition as definedherein.

The present invention further provides a method of synthesising acompound as defined herein, or a pharmaceutically acceptable salt orsolvate thereof.

In another aspect, the present invention provides a compound as definedherein, or a pharmaceutically acceptable salt or solvate thereof,obtainable by, or obtained by, or directly obtained by any one of themethods of synthesis defined herein.

In another aspect, the present invention provides novel intermediatesdefined herein which are suitable for use in any one of the syntheticmethods set out herein.

Preferred, suitable, and optional features of any one particular aspectof the present invention are also preferred, suitable, and optionalfeatures of any other aspect.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

Unless otherwise stated, the following terms used in the specificationand claims have the following meanings set out below.

It is to be appreciated that references to “treating” or “treatment”include prophylaxis as well as the alleviation of established symptomsof a condition. “Treating” or “treatment” of a state, disorder orcondition therefore includes: (1) preventing or delaying the appearanceof clinical symptoms of the state, disorder or condition developing in ahuman that may be afflicted with or predisposed to the state, disorderor condition but does not yet experience or display clinical orsubclinical symptoms of the state, disorder or condition, (2) inhibitingthe state, disorder or condition, i.e., arresting, reducing or delayingthe development of the disease or a relapse thereof (in case ofmaintenance treatment) or at least one clinical or subclinical symptomthereof, or (3) relieving or attenuating the disease, i.e., causingregression of the state, disorder or condition or at least one of itsclinical or subclinical symptoms.

A “therapeutically effective amount” means the amount of a compoundthat, when administered to a mammal for treating a disease, issufficient to effect such treatment for the disease. The“therapeutically effective amount” will vary depending on the compound,the disease and its severity and the age, weight, etc., of the mammal tobe treated.

The term “halo” refers to fluoro, chloro, bromo and iodo.

The phrase “compound of the invention” means those compounds which aredisclosed herein, both generically and specifically.

Compounds of the Invention

In one aspect, the present invention provides a compound of formula Ishown below:

wherein:Q is selected from:

wherein:

-   -   R₁, R_(2a), R_(2b) and R₃ are each independently selected from        hydrogen, halo, methyl, hydroxymethyl, CF₃ and OCF₃; or R_(2a)        and R_(2b) are linked such that together they form a 4, 5 or        6-membered carbocyclic or heterocyclic ring;    -   R₄ and R₅ are each independently selected from hydrogen, halo,        methyl, hydroxymethyl, CF₃ and OCF₃;    -   R₆ and R₇ are each independently selected from hydrogen, halo,        methyl, hydroxymethyl, CF₃ and OCF₃;    -   R₈ and R₉ are each independently selected from hydrogen, methyl,        CF₃ halo, hydroxymethyl and OCF₃;    -   R₁₀ and R₁₁ are each independently selected from hydrogen,        methyl, CF₃ halo, hydroxymethyl and OCF₃;    -   R₁₂ is selected from hydrogen, (1-4C)alkyl or (1-4C)haloalkyl;        or a pharmaceutically acceptable salt thereof.

In another aspect, the present invention provides a compound of formulaI shown below:

wherein:Q is selected from:

wherein:

-   -   R₁, R₂ and R₃ are each independently selected from hydrogen,        halo, methyl, hydroxymethyl, CF₃ and OCF₃;    -   R₄ and R₅ are each independently selected from hydrogen, halo,        methyl, hydroxymethyl, CF₃ and OCF₃;    -   R₆ and R₇ are each independently selected from hydrogen, halo,        methyl, hydroxymethyl, CF₃ and OCF₃;    -   R₈ and R₉ are each independently selected from hydrogen, methyl,        CF₃ halo, hydroxymethyl and OCF₃;        or a pharmaceutically acceptable salt thereof.

In the compounds of formula I above,

indicates the bond that attaches Q to the C(═O) moiety of the compoundof formula I. In all cases, Q is a nitrogen linked heterocyclic ring ofthe formula (i), (ii), (iii), (iv) or (v) shown above.

Particular compounds of the invention include, for example, compounds ofthe formula I, or pharmaceutically acceptable salts or solvates thereof,wherein, unless otherwise stated, each of Q, R₁, R_(2a), R_(2b), R₂, R₃,R₄, R₅, R₆, R₇, R₈, R₉, R₁₀, R₁₁ and R₁₂ has any of the meanings definedhereinbefore or in any one of paragraphs (1) to (33) hereinafter:—

-   (1) Q is selected from:

-   (2) Q is selected from:

-   (3) Q is:

-   (4) Q is of formula (i) and R₁, R₂, R_(2a), R_(2b) and R₃ are each    independently selected from hydrogen, halo, methyl, hydroxymethyl,    CF₃ and OCF₃; or R_(2a) and R_(2b) are linked such that together    they form a 4 or 5 membered carbocyclic or heterocyclic ring;-   (5) Q is of formula (i) and one of R_(2a) or R_(2b) is hydrogen and    the other is selected from hydrogen, fluoro, methyl, hydroxymethyl,    CF₃ and OCF₃; or R_(2a) and R_(2b) are linked such that together    they form a 4 membered heterocyclic ring comprising one N or O atom;-   (6) R₁, R_(2a), R_(2b) and R₃ are each independently selected from    hydrogen, fluoro, methyl, hydroxymethyl, CF₃ and OCF₃;-   (7) R₁, R_(2a), R_(2b) and R₃ are each independently selected from    hydrogen, fluoro, methyl, hydroxymethyl, CF₃ and OCF₃;-   (8) R₁, R_(2a), R_(2b) and R₃ are each independently selected from    hydrogen, fluoro or methyl;-   (9) R₁, R_(2a), R_(2b) and R₃ are all hydrogen;-   (10) one or two of R₁, R_(2a), R_(2b), R₂ and R₃ is a substituent    other than hydrogen;-   (11) one of R₁, R_(2a), R_(2b), R₂ and R₃ is a substituent other    than hydrogen.-   (12) R₁ and R₃ are each independently selected from hydrogen, fluoro    or methyl and R_(2a) and R_(2b) are hydrogen;-   (13) R_(2a) and R_(2b) are hydrogen and one of R₁ and R₃ is selected    from hydrogen, fluoro or methyl and the other is hydrogen;-   (14) R₁, R_(2a) and R₃ are hydrogen and R_(2b) is selected from    hydrogen, fluoro, methyl, hydroxymethyl, CF₃ and OCF₃;-   (15) R₁, R_(2a) and R₃ are hydrogen and R_(2b) is fluoro;-   (16) R₁ and R₃ are hydrogen and R_(2a) and R_(2b) are linked such    that together they form a 4 membered carbocyclic or heterocyclic    ring;-   (17) R₄ and R₅ are each independently selected from hydrogen,    fluoro, methyl, hydroxymethyl, CF₃ and OCF₃;-   (18) R₄ and R₅ are each independently selected from hydrogen, fluoro    or methyl;-   (19) R₄ and R₅ are both hydrogen;-   (20) one of R₄ and R₅ is fluoro or methyl and the other is hydrogen;-   (21) R₆ and R₇ are each independently selected from hydrogen,    fluoro, methyl, hydroxymethyl, CF₃ and OCF₃;-   (22) R₆ and R₇ are each independently selected from hydrogen, fluoro    or methyl;-   (23) R₆ and R₇ are both hydrogen;-   (24) one of R₆ and R₇ is fluoro or methyl and the other is hydrogen.-   (25) R₈ and R₉ are each independently selected from hydrogen or    methyl;-   (26) R₈ and R₉ are both hydrogen;-   (27) one of R₈ and R₉ is methyl and the other is hydrogen;-   (28) R₁₀ and R₁₁ are each independently selected from hydrogen,    fluoro or methyl;-   (29) R₁₀ and R₁₁ are both hydrogen;-   (30) one of R₁₀ and R₁₁ is methyl and the other is hydrogen;-   (31) R₁₀ and R₁₁ are both hydrogen and R₁₂ is methyl;-   (32) R₁₂ is selected from hydrogen or (1-4C)alkyl;-   (33) R₁₂ is methyl.

Suitably, Q is as defined in paragraphs (1), (2) or (3) above. In anembodiment, Q has the structural formula (i). In another embodiment, Qhas the structural formula (ii). In an embodiment, Q has the structuralformula (iii). In a particular embodiment, Q has the structural formula(iv).

In a particular embodiment, Q is as defined in paragraph (3) above.

Suitably when Q is of formula (i), it has the formula shown below:

Suitably, R₁, R_(2a), R_(2b) and R₃ are as defined in any one ofparagraphs (4) to (16) above.

Suitably, R₄ and R₅ are as defined in any one of paragraphs (17) to (20)above. In a particular embodiment, R₄ and R₅ are as defined in paragraph(20) above.

Suitably, R₆ and R₇ are as defined in any one of paragraphs (21) to (24)above. In a particular embodiment, R₆ and R₇ are as defined in paragraph(23) or (24) above.

Suitably, R₈ and R₉ are as defined in any one of paragraphs (25) to (27)above. In a particular embodiment, R₆ and R₇ are as defined in paragraph(26) or (27) above.

Suitably, R₁₀ and R₁₁ are as defined in any one of paragraphs (28) to(30) above. In a particular embodiment, R₆ and R₇ are as defined inparagraph (29) or (30) above.

In a particular group of compounds of the invention, Q is of thestructural formula (iv) shown above. Such compounds have the structuralformula IA below:

wherein R₈ and R₉ each have any one of the definitions set out herein.

In an embodiment of the compounds of formula IA, R₈ and R₉ are eachindependently selected from hydrogen or methyl.

In a further embodiment of the compounds of formula IA, R₈ and R₉ areboth hydrogen.

In a further embodiment of the compounds of formula IA, one of R₈ and R₉is methyl and the other is hydrogen.

Particular compounds of the invention include any one of the following:

-   -   (4-(hydroxy)-3,5-diisopropylphenyl)(morpholino)methanone;    -   (R)-(4-(hydroxy)-3,5-diisopropylphenyl)(2-methylmorpholino)methanone;    -   (3-fluoroazetidin-1-yl) (4-hydroxy-3,5-diisopropyl phenyl)        methanone;    -   (4-(benzyloxy)-3,5-diisopropylphenyl)(piperidin-1-yl)methanone;    -   (4-(hydroxy)-3,5-diisopropylphenyl)(morpholino)methanone;    -   (4-Hydroxy-3,5-diisopropylphenyl)(2-oxa-6-azaspiro[3.3]heptan-6-yl)        methanone;    -   (4-Hydroxy-3-5-diisopropylphenyl)(4-methylpiperazin-1-yl)methanone;        or a pharmaceutically acceptable salt or solvate thereof.

In a particular embodiment, the compounds of the invention is:

(4-(hydroxy)-3,5-diisopropylphenyl) (morpholino) methanone,

or a pharmaceutically acceptable salt or solvate thereof.

The various functional groups and substituents making up the compoundsof the present invention are typically chosen such that the molecularweight of the compound does not exceed 1000. More usually, the molecularweight of the compound will be less than 750, for example less than 700,or less than 650, or less than 600, or less than 550. More preferably,the molecular weight is less than 525 and, for example, is 500 or less.

Suitable or preferred features of any compounds of the present inventionmay also be suitable features of any other aspect.

A suitable pharmaceutically acceptable salt of a compound of theinvention is, for example, an acid-addition salt of a compound of theinvention which is sufficiently basic, for example, an acid-additionsalt with, for example, an inorganic or organic acid, for examplehydrochloric, hydrobromic, sulfuric, phosphoric, trifluoroacetic,formic, citric or maleic acid. In addition a suitable pharmaceuticallyacceptable salt of a compound of the invention which is sufficientlyacidic is an alkali metal salt, for example a sodium or potassium salt,an alkaline earth metal salt, for example a calcium or magnesium salt,an ammonium salt or a salt with an organic base which affords aphysiologically-acceptable cation, for example a salt with methylamine,dimethylamine, trimethylamine, piperidine, morpholine ortris-(2-hydroxyethyl)amine.

Compounds that have the same molecular formula but differ in the natureor sequence of bonding of their atoms or the arrangement of their atomsin space are termed “isomers”. Isomers that differ in the arrangement oftheir atoms in space are termed “stereoisomers”. Stereoisomers that arenot mirror images of one another are termed “diastereomers” and thosethat are non-superimposable mirror images of each other are termed“enantiomers”. When a compound has an asymmetric center, for example, itis bonded to four different groups, a pair of enantiomers is possible.An enantiomer can be characterized by the absolute configuration of itsasymmetric center and is described by the R- and S-sequencing rules ofCahn and Prelog, or by the manner in which the molecule rotates theplane of polarized light and designated as dextrorotatory orlevorotatory (i.e., as (+) or (−)-isomers respectively). A chiralcompound can exist as either individual enantiomer or as a mixturethereof. A mixture containing equal proportions of the enantiomers iscalled a “racemic mixture”.

The compounds of this invention may possess one or more asymmetriccenters; such compounds can therefore be produced as individual (R)- or(S)-stereoisomers or as mixtures thereof. Unless indicated otherwise,the description or naming of a particular compound in the specificationand claims is intended to include both individual enantiomers andmixtures, racemic or otherwise, thereof. The methods for thedetermination of stereochemistry and the separation of stereoisomers arewell-known in the art (see discussion in Chapter 4 of “Advanced OrganicChemistry”, 4th edition J. March, John Wiley and Sons, New York, 2001),for example by synthesis from optically active starting materials or byresolution of a racemic form. Some of the compounds of the invention mayhave geometric isomeric centres (E- and Z-isomers). It is to beunderstood that the present invention encompasses all optical,diastereoisomers and geometric isomers and mixtures thereof that possessactivity.

The present invention also encompasses compounds of the invention asdefined herein which comprise one or more isotopic substitutions. Forexample, H may be in any isotopic form, including ¹H, ²H(D), and ³H (T);C may be in any isotopic form, including ¹²C, ¹³C, and ¹⁴C; and O may bein any isotopic form, including ¹⁶O and ¹⁸O; and the like.

It is also to be understood that certain compounds of the invention mayexist in solvated as well as unsolvated forms such as, for example,hydrated forms. It is to be understood that the invention encompassesall such solvated forms that possess activity.

It is also to be understood that certain compounds of the invention mayexhibit polymorphism, and that the invention encompasses all such formsthat possess activity.

Compounds of the invention may exist in a number of different tautomericforms and references to compounds of the invention include all suchforms. For the avoidance of doubt, where a compound can exist in one ofseveral tautomeric forms, and only one is specifically described orshown, all others are nevertheless embraced by compounds of theinvention. Examples of tautomeric forms include keto-, enol-, andenolate-forms, as in, for example, the following tautomeric pairs:keto/enol (illustrated below), imine/enamine, amide/imino alcohol,amidine/amidine, nitroso/oxime, thioketone/enethiol, andnitro/aci-nitro.

Compounds of the invention containing an amine function may also formN-oxides. A reference herein to a compound of the formula I thatcontains an amine function also includes the N-oxide. Where a compoundcontains several amine functions, one or more than one nitrogen atom maybe oxidised to form an N-oxide. Particular examples of N-oxides are theN-oxides of a tertiary amine or a nitrogen atom of a nitrogen-containingheterocycle. N-Oxides can be formed by treatment of the correspondingamine with an oxidizing agent such as hydrogen peroxide or a per-acid(e.g. a peroxycarboxylic acid), see for example Advanced OrganicChemistry, by Jerry March, 4^(th) Edition, Wiley Interscience, pages.More particularly, N-oxides can be made by the procedure of L. W. Deady(Syn. Comm. 1977, 7, 509-514) in which the amine compound is reactedwith m-chloroperoxybenzoic acid (MCPBA), for example, in an inertsolvent such as dichloromethane.

The compounds of the invention may be administered in the form of apro-drug which is broken down in the human or animal body to release acompound of the invention. A pro-drug may be used to alter the physicalproperties and/or the pharmacokinetic properties of a compound of theinvention. A pro-drug can be formed when the compound of the inventioncontains a suitable group or substituent to which a property-modifyinggroup can be attached. Examples of pro-drugs include in vivo cleavableester derivatives that may be formed at a carboxy group or a hydroxygroup in a compound of the invention and in-vivo cleavable amidederivatives that may be formed at a carboxy group or an amino group in acompound of the invention.

Accordingly, the present invention includes those compounds of theformula I as defined hereinbefore when made available by organicsynthesis and when made available within the human or animal body by wayof cleavage of a pro-drug thereof. Accordingly, the present inventionincludes those compounds of the formula I that are produced by organicsynthetic means and also such compounds that are produced in the humanor animal body by way of metabolism of a precursor compound, that is acompound of the formula I may be a synthetically-produced compound or ametabolically-produced compound.

A suitable pharmaceutically acceptable pro-drug of a compound of theformula I is one that is based on reasonable medical judgement as beingsuitable for administration to the human or animal body withoutundesirable pharmacological activities and without undue toxicity.

Various forms of pro-drug have been described, for example in thefollowing documents:—

a) Methods in Enzymoloqy, Vol. 42, p. 309-396, edited by K. Widder, etal. (Academic Press, 1985);

b) Design of Pro-drugs, edited by H. Bundgaard, (Elsevier, 1985);

c) A Textbook of Drug Design and Development, edited byKrogsgaard-Larsen and H. Bundgaard, Chapter 5 “Design and Application ofPro-drugs”, by H. Bundgaard p. 113-191 (1991);

d) H. Bundgaard, Advanced Drug Delivery Reviews, 8, 1-38 (1992);

e) H. Bundgaard, et al., Journal of Pharmaceutical Sciences, 77, 285(1988);

f) N. Kakeya, et al., Chem. Pharm. Bull., 32, 692 (1984);

g) T. Higuchi and V. Stella, “Pro-Drugs as Novel Delivery Systems”,A.C.S. Symposium Series, Volume 14; and

h) E. Roche (editor), “Bioreversible Carriers in Drug Design”, PergamonPress, 1987.

The in vivo effects of a compound of the formula I may be exerted inpart by one or more metabolites that are formed within the human oranimal body after administration of a compound of the formula I. Asstated hereinbefore, the in vivo effects of a compound of the formula Imay also be exerted by way of metabolism of a precursor compound (apro-drug).

It shall also be appreciated that compounds of formula I may also becovalently linked (at any suitable position) to other groups such as,for example, solubilising moieties (for example, PEG polymers), moietiesthat enable them to be bound to a solid support (such as, for example,biotin-containing moieties), and targeting ligands (such as antibodiesor antibody fragments).

Synthesis

The compounds of the invention can be synthesised using chemistrytechniques that are known in the art.

In the description of the synthetic methods described below and in thereferenced synthetic methods that are used to prepare the staringmaterials, it is to be understood that all proposed reaction conditions,including choice of solvent, reaction atmosphere, reaction temperature,duration of the experiment and workup procedures, can be selected by aperson skilled in the art.

It is understood by one skilled in the art of organic synthesis that thefunctionality present on various portions of the molecule must becompatible with the reagents and reaction conditions utilised.

Necessary starting materials may be obtained by standard procedures oforganic chemistry. The preparation of such starting materials isdescribed in conjunction with the following representative processvariants and within the accompanying Examples. Alternatively necessarystarting materials are obtainable by analogous procedures to thoseillustrated which are within the ordinary skill of an organic chemist.

It will be appreciated that during the synthesis of the compounds of theinvention in the processes defined below, or during the synthesis ofcertain starting materials, it may be desirable to protect certainsubstituent groups to prevent their undesired reaction. The skilledchemist will appreciate when such protection is required, and how suchprotecting groups may be put in place, and later removed.

For examples of protecting groups see one of the many general texts onthe subject, for example, ‘Protective Groups in Organic Synthesis’ byTheodora Green (publisher: John Wiley & Sons). Protecting groups may beremoved by any convenient method described in the literature or known tothe skilled chemist as appropriate for the removal of the protectinggroup in question, such methods being chosen so as to effect removal ofthe protecting group with the minimum disturbance of groups elsewhere inthe molecule.

Thus, if reactants include, for example, groups such as amino, carboxyor hydroxy it may be desirable to protect the group in some of thereactions mentioned herein.

By way of example, a suitable protecting group for an amino oralkylamino group is, for example, an acyl group, for example an alkanoylgroup such as acetyl, an alkoxycarbonyl group, for example amethoxycarbonyl, ethoxycarbonyl or t-butoxycarbonyl group, anarylmethoxycarbonyl group, for example benzyloxycarbonyl, or an aroylgroup, for example benzoyl. The deprotection conditions for the aboveprotecting groups necessarily vary with the choice of protecting group.Thus, for example, an acyl group such as an alkanoyl or alkoxycarbonylgroup or an aroyl group may be removed by, for example, hydrolysis witha suitable base such as an alkali metal hydroxide, for example lithiumor sodium hydroxide. Alternatively an acyl group such as atert-butoxycarbonyl group may be removed, for example, by treatment witha suitable acid as hydrochloric, sulfuric or phosphoric acid ortrifluoroacetic acid and an arylmethoxycarbonyl group such as abenzyloxycarbonyl group may be removed, for example, by hydrogenationover a catalyst such as palladium-on-carbon, or by treatment with aLewis acid for example BF₃.OEt₂. A suitable alternative protecting groupfor a primary amino group is, for example, a phthaloyl group which maybe removed by treatment with an alkylamine, for exampledimethylaminopropylamine, or with hydrazine.

A suitable protecting group for a hydroxy group is, for example, an acylgroup, for example an alkanoyl group such as acetyl, an aroyl group, forexample benzoyl, or an arylmethyl group, for example benzyl. Thedeprotection conditions for the above protecting groups will necessarilyvary with the choice of protecting group. Thus, for example, an acylgroup such as an alkanoyl or an aroyl group may be removed, for example,by hydrolysis with a suitable base such as an alkali metal hydroxide,for example lithium, sodium hydroxide or ammonia. Alternatively anarylmethyl group such as a benzyl group may be removed, for example, byhydrogenation over a catalyst such as palladium-on-carbon.

A suitable protecting group for a carboxy group is, for example, anesterifying group, for example a methyl or an ethyl group which may beremoved, for example, by hydrolysis with a base such as sodiumhydroxide, or for example a t-butyl group which may be removed, forexample, by treatment with an acid, for example an organic acid such astrifluoroacetic acid, or for example a benzyl group which may beremoved, for example, by hydrogenation over a catalyst such aspalladium-on-carbon.

Resins may also be used as a protecting group.

In a particular aspect, the present invention provides a method ofsynthesising a compound of the formula I, or a pharmaceuticallyacceptable salt or solvate thereof, the method comprising:

-   -   a) reacting a compound of formula A

wherein X is a reactive group, such as chloro; and the hydroxyl group isoptionally protected;

with a compound of formula B:H-Q

wherein Q is as defined hereinbefore and the H atom is attached to anitrogen atom of the Q group; and

-   -   b) optionally thereafter, and if necessary:        -   i) removing any protecting groups present;        -   ii) converting the compound formula I into another compound            of formula I; and/or        -   iii) forming a pharmaceutically acceptable salt or solvate            thereof.

X may be any suitable reactive group. Suitably X is a halogen, such aschlorine.

Suitably the coupling reaction between compound A and compound B takesplace in the presence of a suitable solvent. Any suitable solvent orsolvent mixture may be used for this reaction. A person skilled in theart will know how to select suitable solvents or solvent mixtures foruse in these reactions. An example of a suitable solvent isdichloromethane.

A person skilled in the art will be able to select appropriate reactionconditions to use in order to facilitate this reaction. Suitably, thereaction is carried out in anhydrous conditions and in the presence ofan inert atmosphere, such as argon or nitrogen. The reaction may also becarried out at room temperature or at an elevated temperature.

The compound of formula A can be prepared by processes known in the art,and suitably by the processes described herein with reference to theexamples.

The compound of formula B can be prepared by processes known in the art,and suitably by the processes described herein with reference to theexamples.

The resultant compound of formula I can be isolated and purified usingtechniques well known in the art.

The processes defined herein may further comprise the step of subjectingthe compound of formula I to a salt exchange, particularly in situationswhere the compound of formula I is formed as a mixture of different saltforms. The salt exchange suitably comprises immobilising the compound offormula I on a suitable solid support or resin, and eluting thecompounds with an appropriate acid to yield a single salt of thecompound of formula I.

In a further aspect of the invention, there is provided a compound offormula I obtainable by any one of the processes defined herein.

In a further aspect of the invention, there is provided a compound offormula I obtained by any one of the processes defined herein.

In a further aspect of the invention, there is provided a compound offormula I directly obtained by any one of the processes defined herein.

Pharmaceutical Compositions

According to a further aspect of the invention there is provided apharmaceutical composition which comprises a compound of the inventionas defined hereinbefore, or a pharmaceutically acceptable salt orsolvate thereof, in association with a pharmaceutically acceptablediluent or carrier.

The compositions of the invention may be in a form suitable for oral use(for example as tablets, lozenges, hard or soft capsules, aqueous oroily suspensions, emulsions, dispersible powders or granules, syrups orelixirs), for topical use (for example as creams, ointments, gels, oraqueous or oily solutions or suspensions), for administration byinhalation (for example as a finely divided powder or a liquid aerosol),for administration by insufflation (for example as a finely dividedpowder) or for parenteral administration (for example as a sterileaqueous or oily solution for intravenous, subcutaneous, intramuscular,intraperitoneal or intramuscular dosing or as a suppository for rectaldosing).

The compositions of the invention may be obtained by conventionalprocedures using conventional pharmaceutical excipients, well known inthe art. Thus, compositions intended for oral use may contain, forexample, one or more colouring, sweetening, flavouring and/orpreservative agents.

An effective amount of a compound of the present invention for use intherapy of proliferative disease is an amount sufficient tosymptomatically relieve in a warm-blooded animal, particularly a humanthe symptoms of infection, to slow the progression of infection, or toreduce in patients with symptoms of infection the risk of getting worse.

The amount of active ingredient that is combined with one or moreexcipients to produce a single dosage form will necessarily varydepending upon the host treated and the particular route ofadministration. For example, a formulation intended for oraladministration to humans will generally contain, for example, from 0.5mg to 0.5 g of active agent (more suitably from 0.5 to 100 mg, forexample from 1 to 30 mg) compounded with an appropriate and convenientamount of excipients which may vary from about 5 to about 98 percent byweight of the total composition.

The size of the dose for therapeutic or prophylactic purposes of acompound of the formula I will naturally vary according to the natureand severity of the conditions, the age and sex of the animal or patientand the route of administration, according to well-known principles ofmedicine.

In using a compound of the invention for therapeutic or prophylacticpurposes it will generally be administered so that a daily dose in therange, for example, 0.1 mg/kg to 75 mg/kg body weight is received, givenif required in divided doses. In general lower doses will beadministered when a parenteral route is employed. Thus, for example, forintravenous or intraperitoneal administration, a dose in the range, forexample, 0.1 mg/kg to 30 mg/kg body weight will generally be used.Similarly, for administration by inhalation, a dose in the range, forexample, 0.05 mg/kg to 25 mg/kg body weight will be used. Oraladministration may also be suitable, particularly in tablet form.Typically, unit dosage forms will contain about 0.5 mg to 0.5 g of acompound of this invention.

Therapeutic Uses and Applications

In one aspect, the present invention provides a compound of formula I,or a pharmaceutically acceptable salt or solvate thereof, or apharmaceutical composition as defined herein, for use in therapy.

The compounds of the invention are capable of the selective, positiveallosteric modulation of strychnine-sensitive alpha 1-glycine receptors.As will be evident from the example section, the compounds of theinvention target the glycine receptor α1-subunit, which is known to bepositively modulated by anaesthetics, alcohols and cannabinoids, but thecompounds according to the present invention selectively target thisreceptor family with high affinity.

In another aspect, the present invention provides a compound as definedherein, or a pharmaceutically acceptable salt or solvate thereof, or apharmaceutical composition as defined herein, for use in the treatmentof a disease or condition in which the selective, positive allostericmodulation of strychnine-sensitive alpha 1-glycine receptors isbeneficial.

In a particular aspect, the present invention provides a compound asdefined herein, or a pharmaceutically acceptable salt or solvatethereof, or a pharmaceutical composition as defined herein, for use inthe treatment of pain. In a particular embodiment, the pain is presentin a human subject.

In a particular aspect, the present invention provides a compound asdefined herein, or a pharmaceutically acceptable salt or solvatethereof, or a pharmaceutical composition as defined herein, for use inthe treatment of chronic pain, for example lower back pain orneuropathic pain. In a particular embodiment, the chronic pain ispresent in a human subject.

In a particular aspect, the present invention provides a compound asdefined herein, or a pharmaceutically acceptable salt or solvatethereof, or a pharmaceutical composition as defined herein, for use inthe treatment of neuropathic pain. In a particular embodiment, theneuropathic pain is present in a human subject.

In a particular aspect, the present invention provides a compound asdefined herein, or a pharmaceutically acceptable salt or solvatethereof, or a pharmaceutical composition as defined herein, for use inthe treatment of lower back pain. In a particular embodiment, the lowerback pain is present in a human subject.

In another aspect, the present invention provides a compound as definedherein, or a pharmaceutically acceptable salt or solvate thereof, or apharmaceutical composition as defined herein, for use in the selective,positive allosteric modulation of strychnine-sensitive alpha 1-glycinereceptors.

In another aspect, the present invention provides the use of a compoundas defined herein, or a pharmaceutically acceptable salt or solvatethereof, in the manufacture of a medicament for use in the treatment ofa disease or condition in which the selective, positive allostericmodulation of strychnine-sensitive alpha 1-glycine receptors isbeneficial.

In a particular aspect, the present invention provides the use of acompound as defined herein, or a pharmaceutically acceptable salt orsolvate thereof, in the manufacture of a medicament for use in thetreatment of pain. Suitably, the medicament is for use in the treatmentof pain in a human subject.

In a particular aspect, the present invention provides the use of acompound as defined herein, or a pharmaceutically acceptable salt orsolvate thereof, in the manufacture of a medicament for use in thetreatment of chronic pain. Suitably, the medicament is for use in thetreatment of chronic pain in a human subject.

In a particular aspect, the present invention provides the use of acompound as defined herein, or a pharmaceutically acceptable salt orsolvate thereof, in the manufacture of a medicament for use in thetreatment of neuropathic pain. In a particular embodiment, theneuropathic pain is present in a human subject.

In a particular aspect, the present invention provides the use of acompound as defined herein, or a pharmaceutically acceptable salt orsolvate thereof, in the manufacture of a medicament for use in thetreatment of lower back pain. In a particular embodiment, the lower backpain is present in a human subject.

In another aspect, the present invention provides the use of a compoundas defined herein, or a pharmaceutically acceptable salt or solvatethereof, in the manufacture of a medicament for use in the selective,positive allosteric modulation of strychnine-sensitive alpha 1-glycinereceptors.

In another aspect, the present invention provides a method ofselectively producing a positive allosteric modulation effect instrychnine-sensitive alpha 1-glycine receptors in vitro or in vivo, saidmethod comprising contacting a cell with an effective amount of acompound as defined herein, or a pharmaceutically acceptable salt orsolvate thereof.

In another aspect, the present invention provides a method of treating adisease or condition in which the selective, positive allostericmodulation of strychnine-sensitive alpha 1-glycine receptors isbeneficial in a patient in need of such treatment, said methodcomprising administering to said patient a therapeutically effectiveamount of a compound as defined herein, or a pharmaceutically acceptablesalt or solvate thereof, or a pharmaceutical composition as definedherein.

In another aspect, the present invention provides a method of treatingpain in a patient in need of such treatment, said method comprisingadministering to said patient a therapeutically effective amount of acompound as defined herein, or a pharmaceutically acceptable salt orsolvate thereof, or a pharmaceutical composition as defined herein.

In another aspect, the present invention provides a method of treatingchronic pain in a patient in need of such treatment, said methodcomprising administering to said patient a therapeutically effectiveamount of a compound as defined herein, or a pharmaceutically acceptablesalt or solvate thereof, or a pharmaceutical composition as definedherein.

In another aspect, the present invention provides a method of treatingneuropathic pain in a patient in need of such treatment, said methodcomprising administering to said patient a therapeutically effectiveamount of a compound as defined herein, or a pharmaceutically acceptablesalt or solvate thereof, or a pharmaceutical composition as definedherein.

Routes of Administration

The compounds of the invention or pharmaceutical composition comprisingthe active compound may be administered to a subject by any convenientroute of administration, whether systemically/peripherally or topically(ie. at the site of desired action).

Routes of administration include, but are not limited to, oral (e.g, byingestion); buccal; sublingual; transdermal (including, e.g., by apatch, plaster, etc.); transmucosal (including, e.g., by a patch,plaster, etc.); intranasal (e.g., by nasal spray); ocular (e.g., byeyedrops); pulmonary (e.g., by inhalation or insufflation therapy using,e.g., via an aerosol, e.g., through the mouth or nose); rectal (e.g., bysuppository or enema); vaginal (e.g., by pessary); parenteral, forexample, by injection, including subcutaneous, intradermal,intramuscular, intravenous, intraarterial, intracardiac, intrathecal,intraspinal, intracapsular, subcapsular, intraorbital, intraperitoneal,intratracheal, subcuticular, intraarticular, subarachnoid, andintrasternal; by implant of a depot or reservoir, for example,subcutaneously or intramuscularly.

Combination Therapies

The compounds of the invention may be administered as a sole therapy inorder to treat the diseases or conditions identified herein.Alternatively, the therapy may involve the administration of one or moreadditional therapeutic agents (in addition to a compound of theinvention).

For example, the pain treatment defined hereinbefore may involve the useof a compound of the invention as a sole therapy or may involve, inaddition to the compound of the invention, the administration of one ormore additional analgesic and/or anti-inflammatory agents. Examples ofsuitable medicaments include non-steroidal anti-inflammatory drugs andopiate analgesics.

Such conjoint treatment may be achieved by way of the simultaneous,sequential or separate dosing of the individual components of thetreatment. Such combination products employ the compounds of thisinvention within the dosage range described hereinbefore and the otherpharmaceutically-active agent within its approved dosage range.

According to this aspect of the invention there is provided acombination suitable for use in the treatment of pain (e.g. chronicpain) comprising a compound of the invention as defined hereinbefore, ora pharmaceutically acceptable salt or solvate thereof, and anothermedicament.

According to this aspect of the invention there is provided acombination suitable for use in the treatment of pain (e.g. chronicpain) comprising a compound of the invention as defined hereinbefore, ora pharmaceutically acceptable salt or solvate thereof, and anotheranalgesic.

In a further aspect of the invention there is provided a compound of theinvention or a pharmaceutically acceptable salt or solvate thereof, incombination with another medicament for the treatment of pain (e.g.chronic pain).

Herein, where the term “combination” is used it is to be understood thatthis refers to simultaneous, separate or sequential administration. Inone aspect of the invention “combination” refers to simultaneousadministration. In another aspect of the invention “combination” refersto separate administration. In a further aspect of the invention“combination” refers to sequential administration. Where theadministration is sequential or separate, the delay in administering thesecond component should not be such as to lose the beneficial effect ofthe combination.

According to a further aspect of the invention there is provided apharmaceutical composition which comprises a compound of the invention,or a pharmaceutically acceptable salt or solvate thereof, anothermedicament (e.g. another analgesic) and a pharmaceutically acceptablediluent or carrier.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described further in reference to the accompanyingFigures, in which:

FIG. 1 shows the fractional potentiation (y-axis) against concentration(nM; x-axis) for the compound LT-01-25 in the expression andelectrophysiology study described in Example 7 [Y axis: fractionalpotentiation—e.g. 0.75 mean that if a response to glycine alone was 1 μAthen the response to glycine in the present of drug was 1.75 μA];

FIGS. 2A and 2B show the effect of the compound LT-01-25 on pawwithdrawal thresholds to (FIG. 2A) mechanical pressure in neuropathicrats and (FIG. 2B) cold (10° C.) stimulus in neuropathic rats comparedwith lamotrigine (see Example 8(i)); FIG. 3A shows the pharmacokineticprofile (plasma concentration (y-axis) versus time (x-axis)) for theLT-01-25 compound dosed at 10 mg/kg in 10% DMSO/10% Solutol/80% Salinein fasted and non-fasted rats;

FIG. 3B shows the pharmacokinetic profile (plasma concentration (y-axis)versus time (x-axis)) for the LT-01-25 compound dosed at 10 mg/kg in SSVin fasted and non-fasted rats;

FIG. 3C shows the pharmacokinetic profile (plasma concentration (y-axis)versus time (x-axis)) for the LT-01-25 and LT-01-89 (comparator)compounds dosed at 10 mg/kg in SSV in non-fasted rats.

FIGS. 4A and 4B show the comparison in effect of LT-01-25 (Example 1; 10mg/kg p.o.) and LT-01-5 89 (30 mg/kg p.o.) on (FIG. 4A) ipsilateral pawwithdrawal thresholds to mechanical pressure in neuropathic rats and(FIG. 4B) ipsilateral withdrawal latencies to a cold (10° C.) stimulusin neuropathic rats. Male, SD rats. n=6/group. Vehicle: 10% DMSO/10%Solutol HS15/80% saline.

FIG. 5 shows the effect of LT-01-26 (example 6) on percentage reversalto cold (10° C.) stimulus. In all cases fasted, male, Wistar rats wereused (n=6/group). Vehicle: 10% DMSO/10% Solutol HS15/80% saline. 10ml/kg p.o. One-way ANOVA, comparison with time-matched vehicle groupusing Tukey's HSD test * p<0.05, ** p<0.01, *** p<0.001.

FIGS. 6A and 6B show the efficacy of (FIG. 6A) LT-01-25 and (FIG. 6B)Gabapentin-on mechanical allodynia in Streptozocin (STZ) inducedneuropathic rats. In all cases Wistar rats were used (n=2-6). Vehicle:10% DMSO+1% Solutol+80% Saline, p.o. 10 mg/kg. The followingadministrative doses were used; Gabapentin: 30, 60 mg/kg in DSS, p.o. 10ml/kg; and LT-01-25: 3, 10, 30 and 100 mg/kg in DSS, p.o. 10 ml/kg.

EXAMPLES Example 1—Synthesis of(4-(hydroxy)-3,5-diisopropylphenyl)(morpholino)methanone (LT-01-25) Step1—Synthesis of 4-Hydroxy-3-5-diisopropylbenzaldehyde

Hexamethylenetetramine (15.8 g, 56 mmol) was added to a solution of2,6-Diisopropylphenol (10.4 mL) in glacial acetic acid (50 mL) and H₂O(10 mL). The resulting mixture was heated to reflux for 5 minutes andthen short path distillation head was introduced and 10 ml of distillatewas collected. The solution was allowed to continue refluxing for 6 hrsand the reaction was monitored by TLC. Upon completion of the reactionthe solution was cooled to 00° C. and the resulting orange precipitationwas isolated and washed with H₂O (3×50 mL) to afford product as a paleorange solid (10.3 g, 89% yield). ¹H NMR (400 MHz, CDCl₃) δ 9.86 (s,1H), 7.63 (s, 2H), 5.49 (s, 1H), 3.21 (m, 2H), 1.31 (d, J=6.9 Hz, 12H).MS: C₁₃H₁₈O₂ requires 206.3, found 206.3.

Step 2—Synthesis of 4-(benzyloxy)-3,5-diisopropylbenzaldehyde

To a solution of 4-Hydroxy-3-5-diisopropylbenzaldehyde (4.18 g, 20.3mmol) in acetone (50 mL) was added benzyl bromide (2.6 mL, 22.4 mmol)and potassium carbonate (5.6 g, 40.6 mmol). The resulting mixture wasallowed to stir at room temperature for 18 hrs and the reaction wasmonitored by TLC. Upon completion the mixture was filtered throughcelite and the solvent was removed under vacuum. The product waspurified by column chromatography (EtOAc/n-Hexane) to afford the productas an off white solid (5.3 g, 88% yield). ¹H NMR (400 MHz, CDCl₃) δ 9.96(s, 1H), 7.69 (s, 5H), 7.55-7.30 (m, 2H), 4.85 (s, 2H), 3.64-2.96 (m,2H), 1.27 (d, J=6.9 Hz, 12H). MS: C₂₀H₂₄O₂ requires: 319.1679, found:319.1674

Step 3—Synthesis of 4-(benzyloxy)-3,5-diisopropylbenzoic Acid

4-(benzyloxy)-3,5-diisopropylbenzaldehyde (1.74 g, 5.87 mmol) wasdissolved in THF (5 mL) under a blanket of N₂. Selenium dioxide (325 mg,2.94 mmol) was added to the solution along with Hydrogen peroxide (1.5mL, 27 wt %) and the mixture was heated to reflux for 18 hrs. Uponcompletion Pd/C (10 mg) was added and the reaction mixture was allowedto stir for 10 mins. The mixture was filtered through Celite™ and thesolvent was removed under vacuum. The product was purified by columnchromatography (EtOAc/n-Hexane) to afford the product as a white solid(1.6 g, 85% yield). ¹H NMR (400 MHz, CDCl₃) δ 7.92 (s, 2H), 7.57-7.27(m, 5H), 4.85 (s, 2H), 3.49-3.24 (m, 2H), 1.27 (d, J=6.9 Hz, 12H). MS[M+Na]⁺: C₂₀H₂₄O₃ requires: 335.1625, found, 335.1623.

Step 4—Synthesis of 4-(benzyloxy)-3,5-diisopropylbenzoyl Chloride

4-(benzyloxy)-3,5-diisopropylbenzoic acid (200 mg, 0.6 mmol) wasdissolved in DCM (5 mL) under a blanket of N₂. Oxalyl chloride (0.12 mL,0.72 mmol) was added along with DMF (1 drop from a pasture pipette). Thereaction mixture was allowed to stir at room temperature for 2 hrs. Thereaction was monitored by TLC and upon completion the solvent wasremoved under vacuum. The product was not isolated and was taken throughcrude.

Step 5—Synthesis of(4-(benzyloxy)-3,5-diisopropylphenyl)(morpholino)methanone

Morpholine (67 μL, 0.77 mmol) was added to a stirred solution of4-(benzyloxy)-3,5-diisopropylbenzoyl chloride (200 mg, 0.64 mmol) in DCM(5 mL). Et₃N (133 μl, 9.6 mmol) was added and the resulting solution wasallowed to stir at room temperature for 1.5 hours. The reaction wasmonitored by TLC and upon completion the reaction mixture was quenchedwith H₂O (50 mL) and extracted with EtOAc (3×50 mL). The combinedorganic extracts were washed with brine, dried over MgSO₄ and thesolvent was removed under vacuum. The crude product was purified bycolumn chromatography (EtOAc/n-Hexane) to afford the product as a whitesolid (192.9 mg 79% yield). ¹H NMR (400 MHz, CDCl₃) δ 7.54-7.33 (m, 5H),7.18 (s, 2H), 4.80 (s, 2H), 3.73 (s, 8H), 3.45-3.27 (m, 2H), 1.24 (d,J=6.9 Hz, 12H). MS [M+Na]+:C₂₄H₃₁NO₃ requires: 404.2202, found:404.2196.

Step 6—Synthesis of(4-(benzyloxy)-3,5-diisopropylphenyl)(morpholino)methanone (LT-01-25)

(4-(benzyloxy)-3,5-diisopropylphenyl)(morpholino)methanone (520 mg, 1.4mmol) was dissolved in MeOH (10 mL) under a blanket of H₂. Pd/C (32 mg,0.27 mmol) was added and the reaction mixture was allowed to stir for 18hrs. Upon completion the reaction mixture was filtered through Celite™and the solvent was removed under vacuum. The crude product was purifiedby column chromatography (EtOAc/n-Hexane) to afford the product as awhite solid (346 mg, 85% yield). ¹H NMR (400 MHz, CDCl₃) δ 7.14 (s, 2H),5.06 (s, 1H), 3.71 (s, 8H), 3.15 (m, 2H), 1.26 (d, J=6.9 Hz, 12H). ¹³CNMR (101 MHz, CDCl₃) δ 171.74, 151.89, 134.12, 127.40, 123.58, 67.30,27.47, 23.02. MS [M+Na]+:C₁₇H₂₅NO₃ requires: 314.1732, found: 314.1725CHN requires C: 70.07%, H: 8.65%, N: 4.81%, found C: 69.05%, H: 8.54%,N: 4.71%.

Example 2—Synthesis of(R)-(4-(hydroxy)-3,5-diisopropylphenyl)(2-methylmorpholino)methanoneSynthesis of 4-(benzyloxy)-3,5-diisopropylbenzoyl Chloride

4-(benzyloxy)-3,5-diisopropylbenzoic acid (200 mg, 0.6 mmol) wasdissolved in DCM (5 mL) under a blanket of N₂. Oxalyl chloride (0.12 mL,0.72 mmol) was added along with DMF (1 drop from a pasture pipette). Thereaction mixture was allowed to stir at room temperature for 2 hrs. Thereaction was monitored by TLC and upon completion the solvent wasremoved under vacuum. The product was not isolated and was taken throughcrude.

Synthesis of(R)-(4-(Benzyloxy)-3,5-diisopropylphenyl)(2-methylmorpholino)methanone

(R)-2-Mehtylmorpholine hydrochloride (164 mg, 1.19 mmol) was added to astirred solution of 4-(benzyloxy)-3,5-diisopropylbenzoyl chloride (264mg, 0.80 mmol) in DCM (5 mL). Et₃N (332 μl, 2.4 mmol) was added and theresulting solution was allowed to stir at room temperature for 1.5hours. The reaction was monitored by TLC and upon completion thereaction mixture was quenched with H₂O (50 mL) and extracted with EtOAc(3×50 mL). The combined organic extracts were washed with brine, driedover MgSO₄ and the solvent was removed under vacuum. The crude productwas purified by column chromatography (EtOAc/n-Hexane) to afford theproduct as a white solid (151.7 mg 48% yield). ¹H NMR (400 MHz, CDCl₃) δ7.42 (m, 5H), 7.18 (s, 2H), 4.81 (s, 2H), 4.07-3.48 (m, 4H), 3.39 (m,2H), 2.96 (m, 2H), 1.24 (d, J=6.9 Hz, 12H), 1.14 (s, 3H).

Synthesis of(R)-(4-(hydroxy)-3,5-diisopropylphenyl)(2-methylmorpholino)methanone

(4-(benzyloxy)-3,5-diisopropylphenyl)(morpholino)methanone (150 mg, 0.38mmol) was dissolved in MeOH (10 mL) under a blanket of H₂. Pd/C (32 mg,0.27 mmol) was added and the reaction mixture was allowed to stir for 18hrs. Upon completion the reaction mixture was filtered through Celite™and the solvent was removed under vacuum. The crude product was purifiedby column chromatography (EtOAc/n-Hexane) to afford the product as anoff white solid (111 mg, 96% yield). ¹H NMR (400 MHz, CDCl₃) δ 7.13 (s,2H), 5.17 (s, 1H), 3.74 (d, J=127.9 Hz, 4H), 3.22-3.07 (m, 2H), 2.74 (s,1H), 1.26 (d, J=6.8 Hz, 12H), 1.18 (s, 3H). ¹³C NMR (101 MHz, CDCl₃) δ171.43, 152.11, 134.14, 126.52, 123.21, 72.14, 66.68, 26.88, 22.68,18.61. MS [M+Na]⁺:C₁₈H₂₇NO₃ requires: 328.1899, found: 328.1889. CHNrequires C: 70.79%, H: 8.91%, N: 4.59%, found C: 70.56%, H: 8.55%, N:4.61%

Example 3—Synthesis of(3-Fluoroazetidin-1-yl)(4-hydroxy-3,5-diisopropylphenyl)methanoneSynthesis of4-(benzyloxy)-3,5-diisopropylphenyl)(3-fluoroazetidin-1-yl)methanone

3-Fluoroazetidine hydrochloride (2500 mg, 2.25 mmol) was added to astirred solution of 4-(benzyloxy)-3,5-diisopropylbenzoyl chloride(prepared as described in Example 1; 500 mg, 1.5 mmol) in DCM (5 mL).Et₃N (597 μl, 4.5 mmol) was added and the resulting solution was allowedto stir at room temperature for 1.5 hours. The reaction was monitored byTLC and upon completion the reaction mixture was quenched with H₂O (50mL) and extracted with EtOAc (3×50 mL). The combined organic extractswere washed with brine, dried over MgSO₄ and the solvent was removedunder vacuum. The crude product was purified by column chromatography(EtOAc/n-Hexane) to afford the product as a white solid (387.4 mg 70%yield). ¹H NMR (400 MHz, CDCl₃) δ 7.53-7.34 (m, 6H), 5.36 (dddd, J=56.8,9.6, 6.2, 3.5 Hz, 1H), 4.58-4.46 (m, 2H), 4.45-4.30 (m, 2H), 3.44-3.33(m, 2H), 1.24 (d, J=6.9 Hz, 12H).

Synthesis of(3-Fluoroazetidin-1-yl)(4-hydroxy-3,5-diisopropylphenyl)methanone

4-(benzyloxy)-3,5-diisopropylphenyl)(3-fluoroazetidin-1-yl)methanone(387 mg, 1.05 mmol) was dissolved in MeOH (10 mL) under a blanket of H₂.Pd/C (32 mg, 0.27 mmol) was added and the reaction mixture was allowedto stir for 18 hrs. Upon completion the reaction mixture was filteredthrough Celite™ and the solvent was removed under vacuum. The crudeproduct was purified by column chromatography (EtOAc/n-Hexane) to affordthe product as a white solid (223 mg, 76% yield)¹H NMR (400 MHz, CDCl₃)δ 7.36 (s, 2H), 5.66 (s, 1H), 5.36 (dddd, J=56.8, 9.6, 6.2, 3.5 Hz, 1H),4.58-4.26 (m, 4H), 3.26-3.12 (m, 2H), 1.25 (d, J=6.9 Hz, 12H). MS[M+H]⁺:C₁₆H₂₂FNO₃ requires: 280.1711, found: 280.1707.

Example 4—Synthesis of(4-(Benzyloxy)-3,5-diisopropylphenyl)(piperidin-1-yl)methanone Synthesisof 4-(benzyloxy)-3,5-diisopropylbenzoyl Chloride

4-(benzyloxy)-3,5-diisopropylbenzoic acid (200 mg, 0.6 mmol) wasdissolved in DCM (5 mL) under a blanket of N₂. Oxalyl chloride (0.12 mL,0.72 mmol) was added along with DMF (1 drop from a pasture pipette). Thereaction mixture was allowed to stir at room temperature for 2 hrs. Thereaction was monitored by TLC and upon completion the solvent wasremoved under vacuum. The product was not isolated and was taken throughcrude.

Synthesis of(4-(Benzyloxy)-3,5-diisopropylphenyl)(piperidin-1-yl)methanone

Piperidine (230 μL, 2.25 mmol) was added to a stirred solution of4-(benzyloxy)-3,5-diisopropylbenzoyl chloride (500 mg, 1.5 mmol) in DCM(5 mL). Et₃N (310 μl, 2.25 mmol) was added and the resulting solutionwas allowed to stir at room temperature for 1.5 hours. The reaction wasmonitored by TLC and upon completion the reaction mixture was quenchedwith H₂O (50 mL) and extracted with EtOAc (3×50 mL). The combinedorganic extracts were washed with brine, dried over MgSO₄ and thesolvent was removed under vacuum. The crude product was purified bycolumn chromatography (EtOAc/n-Hexane) to afford the product as an offwhite solid (546 mg 95% yield). ¹H NMR (400 MHz, CDCl₃) δ 7.52-7.32 (m,5H), 7.16 (s, 2H), 4.80 (s, 1H), 3.71 (s, 4H), 3.35-3.45 (m, 2H), 1.64(d, J=43.1 Hz, 6H), 1.23 (d, J=6.9 Hz, 12H). [M+H]⁺]⁺:C₂₅H₃₄NO₂requires: 380.2590, found: 380.2575

Synthesis of (4-hydroxy-3,5-diisopropylphenyl)(piperidine-1-yl)methanone

(4-hydroxy-3,5-diisopropylphenyl)(piperidine-1-yl)methanone (520 mg,1.40 mmol) was dissolved in MeOH (10 mL) under a blanket of H₂. Pd/C (32mg, 0.27 mmol) was added and the reaction mixture was allowed to stirfor 18 hrs. Upon completion the reaction mixture was filtered throughCelite™ and the solvent was removed under vacuum. The crude product waspurified by column chromatography (EtOAc/n-Hexane) to afford the productas an off white solid (323 mg, 80% yield). ¹H NMR (400 MHz, CDCl₃) δ7.12 (s, 2H), 4.97 (s, 1H), 3.50 (s, 4H), 3.20-3.08 (m, 2H), 1.64 (d,J=33.5 Hz, 1H), 1.26 (d, J=6.9 Hz, 1H). MS [M+Na]⁺:C₁₈H₂₈NO₂ requires:290.2120, found: 290.2123.

Example 5—Synthesis of(4-Hydroxy-3,5-diisopropylphenyl)(2-oxa-6-azaspiro[3.3]heptan-6-yl)methanoneSynthesis of 4-Hydroxy-3-5-diisopropylbenzoic Acid

NaClO₂ (1.3 g, 14.4 mmol) was added to a solution of4-Hydroxy-3-5-diisopropylbenzaldehyde (1.0 g, 4.8 mmol) NaH₂PO₄ (2.2 g,14.4 mmol) and 2-methyl-2-butene (9.5 mL, 2M in THF) in BuOH/H₂O (1:1,15 mL). The reaction was allowed to stir at room temperature for 16hours. Upon completion the reaction mixture was diluted with Na₂CO₃ (50mL) and was washed with EtOAc (50 mL). The aqueous layer was acidifiedto pH 1 (20 mL HCl, 1 M) and extracted with EtOAc (3×30 mL). The organicextracts were collected and dried over MgSO₄ and concentrated undervacuum to afford the product. The product was purified columnchromatography (EtOAc/n-Hexane) to give the product as a white solid(739 mg, 68% yield). ¹H NMR (400 MHz, CDCl₃) δ 7.85 (s, 2H), 5.30 (s,1H), 3.21-3.11 (m, 2H), 1.30 (d, J=6.8 Hz, 12H). ¹³C NMR (101 MHz,CDCl₃) δ 172.25, 155.07, 133.42, 126.77, 121.39, 27.27, 22.45.MS:C13H18O3 [M+NH₄]⁺ requires 240.2, found 240.2.

Synthesis of 4-(benzyloxy)-3,5-diisopropylbenzoic Acid

4-(benzyloxy)-3,5-diisopropylbenzaldehyde (1.74 g, 5.87 mmol) wasdissolved in THF (5 mL) under a blanket of N₂. Selenium dioxide (325 mg,2.94 mmol) was added to the solution along with hydrogen peroxide (1.5mL, 27 wt %) and the mixture was heated to reflux for 18 hours. Uponcompletion Pd/C (10 mg) was added and the reaction mixture was allowedto stir for 10 mins. The mixture was filtered through Celite™ and thesolvent was removed under vacuum. The product was purified by columnchromatography (EtOAc/n-Hexane) to afford the product as a white solid(1.6 g, 85% yield). ¹H NMR (400 MHz, CDCl₃) δ 7.92 (s, 2H), 7.57-7.27(m, 5H), 4.85 (s, 2H), 3.40 (hept, J=6.8 Hz, 2H), 1.27 (d, J=6.8 Hz,12H). ¹³C NMR (101 MHz, CDCl₃) δ 171.53, 158.06, 142.57, 137.06, 128.65,128.19, 127.43, 126.77, 125.49, 76.51, 26.76, 23.93. MS [M+Na]⁺:C₂₀H₂₄O₃ requires: 335.1625, found: 335.1623

Synthesis of(4-(Benzyloxy)-3,5-diisopropylphenyl)(2-oxa-6-azaspiro[3.3]heptan-6-yl)methanone

To a solution of 4-(benzyloxy)-3,5-diisopropylbenzoic acid (100 mg, 0.32mmol) in DMF (5 mL) was added HATU (180, 0.48 mmol), K₂CO₃ (220 mg, 1.6mmol) and 2-oxa-6-azaspiro[3.3]heptan-6-ium carboxyformate (101 mg, 0.35mmol). The resulting solution was allowed to stir for 1 hour. Uponcompletion the reaction mixture was quenched with H₂O (20 mL) andextracted with EtOAc (3×30 mL). The combined organic extracts werewashed with H₂O (3×30 mL), brine (20 mL), dried over MgSO₄ and thesolvent was removed under vacuum. The crude product was purified bycolumn chromatography (EtOAc/n-Hexane) to afford the product as a whitesolid (62 mg, 50% yield). ¹H NMR (400 MHz, CDCl₃) δ 7.54-7.31 (m, 7H),4.83 (d, J=11.7 Hz, 6H), 4.40 (d, J=42.4 Hz, 4H), 3.39 (hept, J=6.8 Hz,2H), 1.25 (d, J=6.8 Hz, 12H). ¹³C NMR (101 MHz, CDCl₃) δ 170.82, 157.83,142.63, 128.66, 128.31, 127.37, 126.60, 125.44, 72.92, 60.89, 53.37,26.39, 24.02. MS [M+Na]+:C₂₅H₃₁NO₃ requires: 416.2202, found: 416.2186.

Synthesis of(4-Hydroxy-3,5-diisopropylphenyl)(2-oxa-6-azaspiro[3.3]heptan-6-yl)methanone

(4-(Benzyloxy)-3,5-diisopropylphenyl)(2-oxa-6-azaspiro[3.3]heptan-6-yl)methanone(50 mg, 0.13 mmol) was reacted with Pd/C (15 mg, 0.12 mmol) according tothe procedure described in paragraph [00163]. The crude product waspurified by column chromatography (EtOAc/n-Hexane) to afford the productas a white solid (38 mg, 99% yield)¹H NMR (400 MHz, CDCl₃) δ 7.35 (s,2H), 5.43 (s, 1H), 4.82 (s, 4H), 4.39 (d, J=41.9 Hz, 4H), 3.16 (hept,J=6.8 Hz, 2H), 1.26 (d, J=6.8 Hz, 12H). ¹³C NMR (101 MHz, CDCl₃) δ172.27, 154.00, 134.78, 125.74, 125.05, 82.10, 39.57, 28.22, 23.79. MS[M+H]⁺:C₁₈H₂₆NO₃ requires: 304.1907, found: 304.1906. CHN requires C:71.26%, H: 8.31%, N: 4.62%, found C: 71.12%, H: 8.16%, N: 4.38%

Example 6—Synthesis of(4-Hydroxy-3-5-diisopropylphenyl)(4-methylpiperazin-1-yl)methanone

4-Hydroxy-3-5-diisopropylbenzoyl chloride (160 mg, 0.66 mmol) wasreacted with N-methylpiperazine (0.088 mL, 0.80 mmol) according togeneral procedure 1 (below) to afford the product as a brown solid. Thecrude product was purified by trituration with EtOAc (109 mg, 55%yield). m.p.=154-156° C.: ¹H NMR (400 MHz, CDCl₃) δ 7.13 (s, 2H), 5.18(s, 1H), 3.74 (s, 4H), 3.16 (hept, J=6.8 Hz, 2H), 2.44 (s, 4H), 1.26 (d,J=6.8 Hz, 12H). ¹³C NMR (101 MHz, CDCl₃) δ 171.24, 151.59, 133.65,127.18, 123.19, 65.87, 54.82, 45.78, 27.12, 22.62. MS: C₁₈H₂₈N₂O₂requires: 305.2229, found: 305.2224. CHN requires C: 71.02%, H: 9.27%,N: 9.20%, found C: 68.44%, H: 9.03%, N: 8.39%.

General Procedure 1—Amide Coupling

The appropriate morpholine derivative (1.2 eq) was added to a stirredsolution of the acid chloride (1.0 eq) dissolved in DCM (10 mL/g). Et₃N(1.5 eq) was added and the resulting solution was allowed to stir atroom temperature for 1.5 hours. The reaction was monitored by TLC andupon completion the reaction mixture was quenched with H₂O (50 mL) andextracted with EtOAc (3×50 mL). The combined organic extracts werewashed with Na₂CO₃, dried over MgSO₄ and the solvent was removed undervacuum.

Example 7—Expression and Electrophysiological Characterization ofGlycine and GABA Receptor Activity

Human embryonic kidney (HEK) 293 cells (ATCC CRL 1573) and/or Xenopuslaevis oocytes were used for expressing the human a1-3 glycine receptorsubunit as well as human a1, b3, g2 GABA receptor subunit cDNAs insertedinto mammalian expression vectors. Patch- and voltage-clamp recordingfrom receptor expressing cells was performed at a holding potential of−70 mV in normal Ringer solution and digitized for analyses.Dose-response curves of agonist induced peak currents (I) werenormalized to the maximal current value obtained and fitted with thesigmoidal Hill equation using a Gauss Marquardt iteration, where EC50represents the glycine/GABA concentration resulting in a half maximalresponse. Effects of the compounds tested on agonist induced currentswere analysed after superfusing the cells with the respective compoundfor 5 seconds prior to and during agonist application and dose-responsecurves of modulated currents were determined in the presence of agonistconcentrations eliciting a response corresponding to 20% of the maximalinducible current (EC20 value). Results represent means±s.d. and thesignificance of the data was evaluated using Student's paired t test andconsidered to be statistically significant at P<0.05.

The results are shown in FIG. 1 for the compound of Example 1(LT-01-25).

The following EC₅₀ data was obtained for the compounds of Examples 2 to6:

Compound α1 glycine EC₅₀ (nM) Example 2   0.06 +/− 0.01 Example 3   0.43+/− 0.28 Example 5 0.00016 +/− 0.00004 Example 6  0.0012 +/− 0.0004

Example 8—Biological Evaluation for LT-01-25 (Example 1)

(i) In Vivo Assessment of Paw Withdrawal Thresholds for LT-01-25(Example 1)

Animals

All animal procedures were carried out in accordance with the UK Animals(Scientific Procedures) Act 1986 and associated guidelines. Male Wistarrats (initial bodyweight 125-149 g; Harlan UK Ltd) were maintained in acontrolled lighting environment, four to a cage and given food and waterad libitum.

Induction of Neuropathic Pain

Neuropathic pain was induced by partial ligation of the sciatic nerve.Briefly, the rats were anaesthetised (isoflurane/O₂ inhalation), theleft sciatic nerve exposed at mid-thigh level through a small incisionand ⅓ to ½ of the nerve thickness tightly ligated within a 7.0 silksuture. The wound was closed with skin clips. Animals were allowed torecover and tested 12-15 days following surgery.

Behavioural Tests:

Mechanical Hyperalgesia

Mechanical hyperalgesia was examined in a model of neuropathic pain bymeasuring paw withdrawal thresholds (PWT) to increasing mechanical forceapplied to the dorsal surface of the rat paw using an Analgesymeter(Ugo-Basile, Milan) equipped with a wedge-shaped probe (area 1.75 mm²).Cut-off was set at 250 g and the end-point was taken as withdrawal ofthe hind paw. Both ipsilateral and contralateral paw withdrawal readingswere taken.

Cold Sensitivity

Cold sensitivity was assessed using a commercially available cold-plate(Ugo Basile, Milan). The cold-plate was set according to pre-determinedcalibration data using a surface temperature probe to correlate settemperature to actual surface temperature over a wide temperature range(−5° C. to 26° C.). The cold plate was allowed to stabilize for 5minutes at the set temperature prior to testing. Paw withdrawallatencies were determined with the cold-plate set at 10° C. The animalswere lightly restrained and each hind paw in turn placed onto thesurface of the cold-plate. The end point was taken as the withdrawal ofthe paw and recorded as the withdrawal latency for the ipsilateral andthe contralateral paw. A maximum cut-off of 30 seconds was used for eachpaw.

Testing Details and Data Handling

Withdrawal thresholds or latencies were measured on both the ipsilateral(ligated) and contralateral (non-ligated) paws. Treatment groups wererandomised and blinded. Groups of 6 rats were used. Predose behaviouralmeasurements were obtained by measuring paw withdrawals 14 daysfollowing nerve ligation; before the initiation of drug treatment.Following treatment, further readings were taken at 1, 2, 4, 6 and 24hours after drug or vehicle administration.

Data were expressed as withdrawal threshold (g) or withdrawal latencies(s) and percentage reversals calculated according to the followingformula:

${\%\mspace{14mu}{reversal}} = {\frac{{{ipsilateral}\mspace{14mu}{threshold}\mspace{14mu}{postdose}} - {{ipsilateral}\mspace{14mu}{threshold}\mspace{14mu}{predose}}}{{{contralateral}\mspace{14mu}{threshold}\mspace{14mu}{predose}} - {{ipsilateral}\mspace{14mu}{threshold}\mspace{14mu}{predose}}} \times 100}$General Observations

In addition to behavioural pain readings, each rat was observedthroughout the study for changes in general behaviour.

Drug Administration

The compounds were made up in a vehicle containing 10% DMSO/10% SolutolHS15/80% saline. Rats were fasted overnight prior to dosing. Thecompounds were administered by oral gavage at 10 ml/kg bodyweight.Control animals received vehicle alone.

Compound or vehicle solutions were coded and allocated randomly to theanimals (coded A-F) at predose. Data was uncoded and sorted at the endof the experiment.

Statistical Analysis

Statistical analysis was carried out on withdrawal threshold readingsusing ANOVA with repeated measures followed by post-hoc analysis usingTukey's HSD test. The level for statistical significance was set asp<0.05.

Results

The results are shown in FIG. 2.

The LT-01-25 compound produced a marked and long-lasting reversal ofboth the cold (10° C. cold plate) and mechanical (paw pressure)parameters. All three doses of the LT-01-25 compound showed good anddose-related efficacy. Peak reversal of 90% with mechanical occurred at3 h and 93% with cold occurred at 1 h. The positive control,lamotrigine, gave reversals of 65% and 72% in mechanical and coldrespectively.

LT-01-25 therefore showed a significant increase in contralateral pawwithdrawal thresholds to mechanical pressure. At 30 mg/kg, LT-01-25produced increased contralateral paw withdrawal latencies to cold.

There were no apparent drug-induced behavioural side effects.

(ii) Pharmacokinetic Evaluation

Compounds—LT-01-25 (Example 1) and LT-01-89 [a comparator:(4-(hydroxy)-3,5-di-tertbutyl)(morpholino)methanone]

Dose—10 mg/kg (5 mL/kg)

Route—ORAL

Vehicles—10% DMSO/10% Solutol and SSV

Time—24 h

Procedure Number—6

Vehicles

10% DMSO/10% Solutol/80% Saline

-   -   1) Compound was weighed out into a clean vial.    -   2) DMSO was added into the vial; the vial was vortexed and        sonicated it for 15 min.    -   3) Solutol HS 15 was heated at 50° C. until a liquid formed, and        then was added into the vial. The vial was vortexed for 1-2 min.    -   4) 0.9% Saline solution was added to the vial. The vial was        vortexed and then sonicated for 10 min.        Standard Suspension Vehicle (SSV)    -   1) A solution of SSV was made using 0.5% Sodium        carboxymethylcellulose, 0.5% Benzyl alcohol, 0.4% Tween80 and        98.6% saline (0.9%)    -   2) Compound was weighed out into a clean vial    -   3) SSV solution was added into the vial; the vial was vortexed        and sonicated it for 15 min.        Fasted Rats

Fasted rats were fasted overnight and given access to food immediatelyafter dosing.

Protocol

-   -   1) Rats were manually restrained and given a 10 mg/kg oral dose        of compound at 5 mL/kg.    -   2) At designated time points (0.25, 0.5, 1, 3, 5, 7 and 24        hours) the rats were anaesthetised using isoflurane.    -   3) Approximately 300 μL of blood was taken from the tail vein        using a 1.5 inch needle treated with heparin and collected into        1.5 mL eppendorf tubes.    -   4) After sampling, pressure was applied to the puncture until        bleeding ceased. The animals were returned to their cages and        given free access to food and water.    -   5) Blood samples were stored on ice and then centrifuged at        13,000 rpm for 15 min to separate the plasma.    -   6) 150 μL of the plasma was treated with 300 μL of ACN:MeOH        (1:1) solution containing the internal standard. The samples        were then centrifuged for a further 15 min at 13,000 rpm.    -   7) 200 μL of the supernatant was collected and placed in LC-MS        vials for analysis. All samples were stored at −80° C.        Results

The results for the LT-01-25 compound dosed at 10 mg/kg in 10% DMSO/10%Solutol/80% Saline in fasted and non-fasted rats are shown in FIG. 3Aand in Table 1 shown below.

TABLE 1 PK Parameters Non-Fasted 10% DMSO Fasted 10% DMSO Half Life (hr)1.4 1.4 Cmax (ng/mL) 1710.8 2415.5 Tmax (hr) 4 0.3 AUC∞ (area)(ng-hr/mL) 20421.4 8532.8 Vd (area)/kg (mL/kg) 973.7 2300.6 CL (area)/kg(mL/hr/kg) 505.4 1171.9

The results for the LT-01-25 compound dosed at 10 mg/kg in SSV in fastedand non-fasted rats are shown in FIG. 3B and in Table 2 shown below.

TABLE 2 PK Parameters Non-Fasted SSV Fasted SSV Half Life (hr) 3.62 1.4Cmax (ng/mL) 2124 2592.6 Tmax (hr) 0.25 1 AUC∞ (area) (ng-hr/mL) 19032.818130 Vd (area)/kg (mL/kg) 2710.9 1142.6 CL (area)/kg (mL/hr/kg) 519.7551.6

The results for the LT-01-25 and LT-01-89 (comparator) compounds dosedat 10 mg/kg in SSV in non-fasted rats are shown in FIG. 3C and in Table3 shown below.

TABLE 3 PK Parameters L1-01-89 LT-01-25 Half Life (hr) 20.4 3.6 Cmax(ng/mL) 471.2 2124.0 Tmax (hr) 1.2 0.3 AUC∞ (area) (ng-hr/mL) 5931.719032.8 Vd (area)/kg (mL/kg) 32729.9 2710.9 CL (area)/kg (mL/hr/kg)1076.8 519.7(iii) In Vivo Model of Neuropathic Pain: Reversal of Tactile Allodynia

A comparison of LT-01-25 (Example 1) and L1-01-89 was conducted usingthe following protocol:

Summary:

-   -   1) In rats a peripheral neuropathy was induced by partial        ligation of the sciatic nerve in one hind limb.    -   2) Two weeks (12-15 days) after induction of peripheral        neuropathy stable mechanical (tactile) allodynia was induced in        the hind paw of the affected limb.    -   3) Five treatment groups of male SD rats (n=8) were used:        vehicle control (drug formulation), 3 drug doses, and a positive        control, lamotrigine (30 mg/kg). Animals were randomized between        groups and the experiment was carried out using blinded        conditions. The study was split with n=4/group in each        experiment.    -   4) Baseline behavioural measurements were obtained prior to        surgery and at intervals post-surgery. Predose behavioural        measurements were obtained by measuring paw withdrawal        thresholds 12-15 days following nerve ligation.    -   5) Compound efficacy was determined by measuring paw withdrawal        thresholds at specified intervals following vehicle/compound        treatment.        Methods        Animals

All animal procedures were carried out in accordance with the UK Animals(Scientific Procedures) Act 1986 and associated guidelines. Animals weremaintained in a controlled lighting environment and given food and waterad libitum. Male Sprague Dawley rats (120-140 g at time of surgery) wereused.

Drug Administration

Rats were fasted overnight with free access to water and fed 4 hourspost-dose.

Tests compounds as well as Lamotrigine (30 mg/kg, volume: 10 ml/kg))were prepared in the designated formulation (10% DMSO, Solutol HS 15/80%and 0.9% saline for p.o. administration) and administered via the chosenroute.

Induction of Neuropathic Tactile Allodynia

Allodynia was examined in the model of neuropathic pain induced bypartial ligation of the sciatic nerve as described by Seltzer et al(1990). Rats were anaesthetised (isoflurane/O2 inhalation), the leftsciatic nerve was exposed at mid-thigh level through a small incisionand ⅓ to ½ of the nerve thickness tightly ligated within a 7.0 silksuture. The wound was closed with skin clips. Animals were allowed torecover and compounds administered 12-15 days following surgery.

Behavioural Tests

Tactile allodynia was assessed by measuring withdrawal thresholds tocalibrated von Frey hairs. As a force higher than 15 g can lift the pawas well as eliciting a response, 15 g represented the cut-off point.Animals were placed into a perspex chamber with metal grid floor givingaccess to the underside of their paws and allowed to acclimatise priorto the start of the experiment. Tactile allodynia was tested by touchingthe plantar surface of the hind paw with von Frey hairs in ascendingorder of force for up to 6 seconds. A positive response was noted if thepaw is sharply withdrawn or there was flinching upon removal of thehair. Once a positive withdrawal response had been established, the pawwas re-tested, starting with the next descending von Frey hair until noresponse occurred. The lowest amount of force required to elicit aresponse was recorded as the paw withdrawal threshold (in grams).

Data were also expressed as percentage of the maximum possible effect (%MPE) defined as:

Allodynia was measured on both the ipsilateral (ligated) andcontralateral (non-ligated) paw prior to (pre-dose) and at a set timepoint following compound or vehicle administration (post-dose).Treatment groups were randomised and blinded. Groups of eight rats wereused.

Predose behavioural measurements were obtained by measuring pawwithdrawal thresholds 12-15 days following nerve ligation; before theinitiation of drug treatment.

Compound/vehicle were administered at specified doses. Followingtreatment, further readings were taken; 1, 3, 6 and 24 hour after p.o.administration.

Statistical Analysis

Raw data were analysed using parametric statistical tests, includingone-way analysis of variance (ANOVA) followed by Tukey's post hoc testrepeated measures of ANOVA.

P<0:05 was set as the level of statistical significance.

Reference: Seltzer Z, Dubner R, Shir Y. A novel behavioural model ofneuropathic pain disorders produced in rats by partial sciatic nerveinjury. Pain 1990; 43:205±218.

Results

The results are shown in FIG. 4 and Table 4 below:

TABLE 4 comparison of LT-01-25 and L1-01-89 LT-01-25 (10 mg/kg) LT-01-89(30 mg/kg) Mechanical pressure 1 hr - - - 80% 1 hr - - - 70% Percentagereversal of predose 3 hr - - - 90% 3 hr - - - 50% hyperalgesia 6hr - - - 40% 6 hr - - - 20% Cold (10° C.) Stimulus 1 hr - - - 85% 1hr - - - 70% Percentage reversal of predose 3 hr - - - 35% 3 hr - - -65% Hyperalgesia after 1 hr 6 hr - - - 35% 6 hr - - - 10%(iv) Cerebrospinal Fluid (CSF) and Plasma Levels

Test system SD rat, 243-272 g, male, N = 9, purchased from SLACLaboratory Animal Co. LTD Food status Fasted overnight, free access towater and fed 4 hr post dose. Administration PO: 3 mg/kg (10 mL/kg) viaoral gavage (N = 9) Blood collection The animal was restrained manuallyat the designated time points, approximately 150 μL of blood sample wascollected via cardioac puncture into EDTA-2K tubes. The blood sampleswere maintained in wet ice first and centrifuged to obtain plasma (2000g, 4° C., 10 min) within 30 minutes post sampling. CSF collection 1. Theanimal was euthanized under pure CO₂. 2. The CSF was collected by directpuncture of butterfly needle into the cisterna magna, using theoccipital bone and the wings of the atlas as landmarks. 3. A piece ofwhite paper was used as a background to monitor color change in thesample just above the needle during collection. 4. Upon observation ofcolor change, the PE tubing was quickly clamped off above the colorchange and cut just above the clamped site. The clear sample is drawninto the syringe. Sample storage and Plasma samples will be stored indry ice temporarily and transferred into- disposition 80° C. freezer forlong term preservation. The backup samples will be discarded after 3weeks unless specified. The unused dosing solutions will be stored at 4°C. fridge and discarded within 1 week after completion of the study.Results

The results are shown in Table 5 below.

TABLE 5 CSF data for LT-01-25 and L1-01-89 (comparator) LT-01-25LT-01-89 CSF levels (p.o. dose 3 95 ng/mL 27 ng/mL mg/kg after 2 hr)(900 × EC₅₀) (180 × EC₅₀)(v) Microsomal Stability Data

Rat and human microsomal stability data was obtained using wellestablished protocols known to those skilled in the art.

The human microsomal stability protocol is detailed below.

Human Microsomal Data

Incubation Methods

The metabolic stability assay was performed by incubating each testcompound (1 μM) with human liver microsomes in duplicate at 37° C. and0.4 mg/mL protein concentration. The metabolic reaction was initiated bythe addition of a NADPH-regenerating system (i.e. NADPH is the cofactorrequired for CYP450-mediated metabolism) and quenched at various timepoints over the 60 minute incubation period by the addition ofacetonitrile. Control samples (containing no NADPH) were included (andquenched at 2, 30 and 60 minutes) to monitor for potential degradationin the absence of cofactor. Samples were analysed by UPLC-MS(Waters/Micromass Xevo G2 QTOF) under positive electrospray ionisationand MS spectral data acquired in a mass range of 80 to 1200 Daltons.

Calculations

Test compound concentration versus time data were fitted to anexponential decay function to determine the first-order rate constantfor substrate depletion. In cases where clear deviation from first-orderkinetics was evident, only the initial linear portion of the profile wasutilised to determine the degradation rate constant (k). Each substratedepletion rate constant was then used to calculate: [1] a degradationhalf-life, [2] an in vitro intrinsic clearance value (CLint, in vitro);[3] a predicted in vivo hepatic intrinsic clearance value (CLint); [4] apredicted in vivo blood clearance value (CLblood); and [5] a predictedin vivo hepatic extraction ratio (EH).

[1] $t_{1/2} = \frac{\ln(2)}{k}$ [2]${CL}_{{int},\;{{in}\mspace{14mu}{vitro}}} = \frac{k}{{microsomal}\mspace{14mu}{protein}\mspace{14mu}{content}\mspace{14mu}\left( {0.4\mspace{14mu}{mg}\mspace{14mu}{protein}\text{/}{mL}} \right)}$[3]^(*)${CL}_{int} = {{CL}_{{int},\;{{in}\mspace{14mu}{vitro}}} \times \frac{{liver}\mspace{14mu}{mass}\mspace{11mu}(g)}{{body}\mspace{14mu}{weight}\mspace{11mu}({kg})} \times \frac{{mg}\mspace{14mu}{microsomal}\mspace{14mu}{protein}}{g\mspace{14mu}{liver}\mspace{14mu}{mass}}}$[4]^(*) ${CL}_{blood} = \frac{Q \times {CL}_{int}}{Q + {CL}_{int}}$[5]^(*)$E_{H} = {\frac{{CL}_{blood}}{Q} = \frac{{CL}_{int}}{Q + {CL}_{int}}}$^(*)The following scaling parameters^(a) were assumed in the abovecalculations: Liver Mass Microsomal Hepatic blood flow (Q) (g liver/kgprotein (mL/min/kg Species body weight) (mg/g liver mass) body weight)Human 25.7 32 20.7 ^(a)Ring et al. (2011) Journal of PharmaceuticalSciences, 100:4090-4110. NOTE: Calculations of intrinsic clearance arebased on the “in vitro T_(1/2) method” (Obach, 1999, Drug Metab. Dispos.27: 1350-1359), which assumes: 1) The substrate concentration employedis well below the apparent K_(M) for substrate turnover; and, 2) Thereis no significant product inhibition, nor is there any mechanism-basedinactivation of enzyme. The use of hepatic microsomes in the predictionof the in vivo hepatic extraction ratio has two further inherentassumptions (Obach, 1999) which: 1) NADPH-dependent oxidative metabolismpredominates over other metabolic routes (i.e. direct conjugativemetabolism, reduction, hydrolysis, etc.); and, 2) Rates of metabolismand enzyme activities in vitro are truly reflective of those that existin vivo. Data should be considered within these terms of reference.

The limit of sensitivity of this assay corresponds to 15% loss ofcompound over the assay duration. For compounds showing <15% loss over60 minutes (i.e. degradation half-life >247 min), metabolic stabilityparameters based on 0.4 mg/mL microsomal protein concentration arereported as below:

In vitro CL_(int) Microsome-Predicted Species (μL/min/mg protein) E_(H)Human <7 <0.22 Rat <7 <0.15 Mouse <7 <0.13ResultsThe results for the rat and human microsomal studies are shown in Table6 below:

TABLE 6 Rat and human microsomal data for LT-01-25 and L1-01-89(comparator) Microsome used LT-01-25 L1-01-89 Rat microsomes 741 min,121 min (1 μM) (t_(1/2)), CI 3.35 mL/min/kg 20.38 mL/min/kg 1155 min(t_(1/2))* 165 min (t_(1/2))* 1.07 mL/min/kg (CI)* 5.26 mL/min/kg (CI)*human microsomes 495 min (t_(1/2))* 138.6 min (t_(1/2))* (1 μM)(t_(1/2)), CI 2.7 mL/min/kg (CI)* 6.2 mL/min/kg (CI)*

Example 9—Biological Evaluation of LT-01-26 (Example 6)

The effect of LT-01-26 on percentage reversal to cold (10° C.) stimuluswas investigated using the protocol described in Example 8, section(iii) above. In all cases fasted, male, Wistar rats were used(n=6/group). The vehicle was 10% DMSO/10% Solutol HS15/80% saline. 10ml/kg p.o. was administered. The results were subject to one-way ANOVA,comparison with time-matched vehicle group using Tukey's HSD test *p<0.05, ** p<0.01, *** p<0.001.

Results

The results are shown in FIG. 5.

Example 10—Streptozocin-Induced Diabetic Neuropathic Pain Model

The efficacy of LT-01-25 on mechanical allodynia in Streptozocin (STZ)induced neuropathic rats was measured using the methodology describedbelow. Comparative data for the efficacy of Gabapentin (Gbp) was alsogenerated.

Method

Mechanical allodynia was measured using hindpaw withdrawal threshold(PWT) using von Frey hair test. In all cases Wistar rats (˜200 g, SLAC)were used. Streptozocin, obtained from Sigma, was injectedintraperitoneally (IP injection) at time zero (0 days). An effect amountof 60 mg/kg of Streptozocin was injected. PWT and blood glucose testswere then measured after 7 days (blank (BL)) before the vehicle orcompound was administered and further PWT measurements were taken ateither 1, 3, 4 and 6 hours, 1, 3 and 6 hours or 3, 6, 9 and 12 hoursafter vehicle or compound administration.

Compounds Used:

Vehicle II (DSS): 10% DMSO+1% Solutol+80% Saline, p.o. 10 mg/kg

Gabapentin: 30, 60 mg/kg in DSS, p.o. 10 ml/kg

LT-01-25: 3, 10, 30 and 100 mg/kg in DSS, p.o. 10 ml/kg

Results

The results are shown in FIGS. 6(a) and 6(b).

The invention claimed is:
 1. A compound of formula (I) shown below:

wherein: Q is:

wherein:

indicates the point of attachment to the C(═O) moiety of the compound offormula I; and R₁, R_(2a), R_(2b) and R₃ are each independently selectedfrom hydrogen, halo, methyl, hydroxymethyl, CF₃ and OCF₃; or R_(2a) andR_(2b) are linked such that together they form a 4, 5 or 6- memberedcarbocyclic or heterocyclic ring; or a pharmaceutically acceptable saltthereof.
 2. A compound according to claim 1, wherein R₁, R_(2a), R_(2b)and R₃ are each independently selected from hydrogen, fluoro or methyl;or R_(2a) and R_(2b) are linked such that together they form a 4 or 5membered carbocyclic or heterocyclic ring.
 3. A compound according toclaim 1, wherein R₁, R_(2a), R_(2b) and R₃ are all hydrogen; or R_(2a)and R_(2b) are linked such that together they form a 4 or 5 memberedheterocyclic ring.
 4. A compound according to claim 1, wherein one ortwo of R₁, R_(2a), R_(2b) and R₃ is a substituent other than hydrogen.5. A compound according to claim 1, wherein R₁ and R₃ are hydrogen andone of R_(2a) and R_(2b) is fluoro.
 6. A compound according to claim 1,which is selected from any one of the following:(3-fluoroazetidin-1-yl)(4-hydroxy-3,5-diisopropylphenyl)methanone; and(4-Hydroxy-3,5-diisopropylphenyl)(2-oxa-6-azaspiro[3.3]heptan-6-yl)methanone;or a pharmaceutically acceptable salt or solvate thereof.
 7. Apharmaceutical composition comprising a compound according to claim 1,or a pharmaceutically acceptable salt thereof, in admixture with apharmaceutically acceptable diluent or carrier.
 8. A method of treatingchronic pain or inducing anaesthesia in a patient in need of suchtreatment, said method comprising administering to said patient atherapeutically effective amount of a compound according to claim
 1. 9.A method of synthesising a compound of claim 1, or a pharmaceuticallyacceptable salt or solvate thereof, the method comprising: a) reacting acompound of formula A

wherein X is a reactive group, for example chloro; and the hydroxylgroup is optionally protected; with a compound of formula B:H-Q wherein the H atom is attached to a nitrogen atom of the Q group.10. A pharmaceutical composition comprising a compound according toclaim 6, or a pharmaceutically acceptable salt thereof, in admixturewith a pharmaceutically acceptable diluent or carrier.
 11. A method oftreating chronic pain or inducing anaesthesia in a patient in need ofsuch treatment, said method comprising administering to said patient atherapeutically effective amount of a compound according to claim
 6. 12.A compound according to claim 1, wherein R₁, R_(2a), R_(2b) and R₃ areeach independently selected from hydrogen or fluoro.
 13. A compoundaccording to claim 1, wherein R_(2a) and R_(2b) are linked such thattogether they form a 4 or 5 membered carbocyclic or heterocyclic ring.14. A compound according to claim 1 which is(3-fluoroazetidin-1-yl)(4-hydroxy-3,5-diisopropylphenyl)methanone, or apharmaceutically acceptable salt or solvate thereof.
 15. A compoundaccording to claim 1 which is(4-hydroxy-3,5-diisopropylphenyl)(2-oxa-6-azaspiro[3.3]heptan-6-yl)methanone,or a pharmaceutically acceptable salt or solvate thereof.